A strong early season cold front dropped across the state from the northwest, which generated strong and nearly stationary thunderstorms. These storms produced high rainfall rates that resulted in some flash flooding impacts.
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Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS HFO wrote it up.
A strong early season cold front dropped across the state from the northwest, which generated strong and nearly stationary thunderstorms. These storms produced high rainfall rates that resulted in some flash flooding impacts.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Honolulu, HI wrote its last area forecast discussion before the first event at Dec 18, 10:00 AM HST, 5 hours 50 minutes earlier.
Area Forecast Discussion National Weather Service Honolulu HI 1000 AM HST Sun Dec 18 2022 .SYNOPSIS... Numerous showers and thunderstorms will continue through Monday. Some storms may be severe tonight and Monday. Any severe storms will be capable of producing strong winds and hail. Strong and damaging southwest, or kona, winds will develop tonight and continue through Monday. Periods of heavy rain throughout this time may result in areas of flash flooding. Weather will gradually improve Tuesday with fair weather and much lighter winds expected by Wednesday. && .DISCUSSION... Satellite imagery shows an impressive mid-latitude cyclone deepening over the Central Pacific Basin as it digs southeastward toward the islands. Ahead of this cyclone, we have increasing southerly winds this morning which is pulling moisture from the tropics and producing widespread moderate rainfall with brief periods of heavy rainfall across the smaller islands. The moisture axis remains centered over the western half of the state this morning, but as I write this discussion we are already seeing the moisture axis shift eastward towards Maui County. With the moisture shifting east and instability increasing throughout the day, Oahu, Maui County and the Kona side of the Big Island should see increasing rainfall today with pockets of heavy rain. A Flood Watch is in effect for all Hawaiian Islands through Monday night. Winds will also be increasing from the southwest at the surface and aloft this afternoon which will increase the storm motion. This should help decrease the flooding threat slightly, but with the widespread rainfall from this morning saturating the soils already, it would only take one intense thunderstorm sitting over a particular area briefly to cause flooding concerns. The main weather concern looks to start from this evening and continue through Monday. As the mid-latitude cyclone continues to move closer to the state, kona winds will increase with sustained southwest surface winds of 20 to 30 mph with stronger gusts expected. In areas of local accelerations, such as the Windward zones and areas downwind of terrain will be highly susceptible to downsloping which will force damaging winds to the surface. Wind gusts of over 60 mph will be possible especially over Windward Oahu and downwind of Mt.Kaala, north and east Maui, and north and east Big Island. Convective instability will also be maximized during this time as 0-1km MLCAPE increases to at least 1500 j/kg. Any particularly vigorous showers will therefore have the potential to mix down severe winds up to 60 mph. For this reason, the High Wind Warning includes the entire area - not only favored downsloping areas. Finally, a severe thunderstorm threat will exist tonight through through the time of frontal passage on Monday. Lapse rates aloft are modeled to remain fairly impressive, in the neighborhood of 7 to 7.5 km/C in the prefrontal environment. Strong, deep unidirectional wind profiles in the presence of moderate convective instability will contribute to an enhanced threat for thunderstorms to evolve into northeast-moving bowing segments capable of producing damaging straight line winds. 0-6km bulk shear in excess of 40 kts and cold temperatures aloft will also support a marginal risk for hail up to 1 inch in diameter. The potential for a Severe Thunderstorm Watch will be evaluated today and this evening. Tuesday into midweek. Well-mixed, gusty westerlies build in behind the cold front and focus showers over leeward slopes through Tuesday. Fair weather with much lighter winds are expected by Wednesday. Beyond Wednesday, we are looking at a progressive pattern to continue in the North Pacific, which will keep trade winds out of the forecast through rest of the week. Another front could approach the state towards the end of the week, through most of the moisture and instability looks to stay well north of the state. && .AVIATION... A strong cold front and upper level trough associated with an impressive low pressure system far north of the main Hawaiian Islands will advance towards Kauai through tonight. Ahead of this feature, enhanced moisture has overspread the smaller islands from Kauai to Maui this morning, producing widespread MVFR ceilings and visibilities and occasional IFR conditions within heavier downpours. With ample instability in the area, thunderstorms have also been observed, especially across adjacent waters. Lightning, heavy rain, and moderate to severe turbulence have all been reported via PIREPs at various locations. As a result, SIGMET Victor has been issued for embedded thunderstorms over a large portion of the state. This SIGMET will likely remain in effect at least through the rest of the morning, though the bulk of lightning is now greater than 40nm NNE of the island chain. Expect clouds and showers with scattered thunderstorms to continue as the enhanced moisture eventually makes its way further south to the Big Island later this afternoon. Widespread MVFR ceilings and visibilities with occasional IFR conditions will persist for much of the day and into tonight across a large portion of the state. Additionally, as the front gets closer to the state, southwest wind speeds are expected to increase today and become strong through tonight. AIRMET Sierra for mountain obscuration above 2500 feet remains in effect for Kauai, Oahu, Molokai, and Maui. This AIRMET will likely remain in effect through the afternoon and may need to be expanded to also include the Big Island later today. In addition, as the gusty southwest winds increase later today, AIRMET Tango will likely be needed for TEMPO moderate mechanical turbulence northwest through southeast of the higher terrain on most islands. Once it is issued, this AIRMET will likely remain in effect into Monday. There is also potential for sustained surface wind speeds to reach 30kts or greater overnight for portions of the state, which would warrant an AIRMET for strong winds as well. Finally, model data suggests that moderate to severe clear-air turbulence will be possible behind the main area of showers this afternoon into early evening. Should this materialize, an AIRMET for moderate upper level turbulence or possibly a SIGMET for severe turbulence from roughly Kauai to Oahu would be needed. && .MARINE... A robust cold front will move southeast across the islands tonight through Monday night, bringing a wide array of marine hazards. These include the potential for gusty winds and hail in and around strong to severe thunderstorms, sustained near-gale to gale-force southwest to west winds, as well as rapidly increasing seas and surf. A Small Craft Advisory (SCA) remains in effect for all Hawaiian waters through this afternoon, but will be replaced by a Gale Warning tonight. Additionally, a High Surf Warning (HSW) for exposed north and west facing shores will go into effect tonight. Less-exposed shorelines may need a High Surf Advisory (HSA) as the swell builds. Even after the front moves east of the islands, west winds are expected to remain strong to near-gale on Tuesday as low pressure passes a couple hundred miles north of the islands. Winds will decline Tuesday night into Wednesday as the low departs to the northeast and a ridge builds over the area. The strong low pushing the cold front over the islands will produce a long-lived and extra-large northwest swell that will bring surf heights well above High Surf Warning (HSW) levels. There is high potential for wave run-up onto vulnerable roadways and coastal areas in the HSW areas, with the most likely time for these impacts being Monday night into Tuesday morning during high tide. This swell is expected to drop below warning thresholds Tuesday night into Wednesday, but a large northwest swell is possible during the second half of next week. Surf along south and west facing shores will also see an increase in short-period wind waves Sunday evening into Tuesday due to the strong onshore winds. && .HFO WATCHES/WARNINGS/ADVISORIES... Flood Watch through late Monday night for all Hawaiian Islands. High Wind Warning from 6 PM this evening to 6 PM HST Monday for all Hawaiian Islands. High Surf Warning from 6 PM this evening to 6 PM HST Tuesday for Niihau-Kauai Leeward-Waianae Coast-Oahu North Shore-Olomana-Maui Windward West-Kauai North-Molokai Windward-Molokai North-Molokai West-Windward Haleakala. High Wind Warning until 6 AM HST Tuesday for Haleakala Summit. High Wind Warning until 6 AM HST Wednesday for Big Island Summits. Winter Storm Warning from 6 PM this evening to 6 AM HST Tuesday for Big Island Summits. Small Craft Advisory until 6 PM HST this evening for all Hawaiian waters- Gale Warning from 6 PM this evening to 6 PM HST Monday for all Hawaiian waters- && DISCUSSION...Kino/JVC AVIATION...Vaughan MARINE...Powell
PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
116 PM HST SUN DEC 18 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1243 PM NON-TSTM WND GST 4 SE WAIALUA 21.54N 158.08W
12/18/2022 U0.00 MPH HONOLULU HI COUNTY OFFICIAL
A TREE FELL ACROSS KAUKONAHUA ROAD NEAR POAMOHO STREET.
&&
JNSPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE HONOLULU HI
245 PM HST SUN DEC 18 2022
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0242 PM HEAVY RAIN 7 NW KAUNAKAKAI 21.15N 157.10W
12/18/2022 M4.34 INCH MAUI HI ASOS
10 HOUR RAINFALL ENDING 2:30 PM HST.
&&
SWRThe Molokai radar (PHMO), 85 km away, was scanning. The volume nearest the first event began at 01:51 UTC.
6 flash flood. Local standard time, as filed.
South Kihei Road was closed between Kulanihakoi Street and Kanoulu Street, as well as south to Kulanihakoi Street.
Pillani Highway was closed from the town of Kipahulu to Ulupalakua due to heavy rainfall. Additionally, in the Kaupo/Kipahulu area, the road was washed out about a mile east of Kaupo Gulch.
Highway 270 was closed between mile markers 10 and 11 due to debris on the road resulting from heavy rainfall.
Emergency management reported the upper portion of Palani Rd. was flooded.
Waikoloa Village was flooded along Waikoloa Road near the Paniolo Avenue intersection. Also, Highway 190 was closed near mile marker 5-6 due to debris on the road.
Kawaihae Road near the Kohala Mountain Road junction was flooded.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Hawaii in 2022Every state in 2022This day in weather historyWarnings in Hawaii, December 2022
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1067452, 1067453, 1067441, 1067423, 1067434, 1067436.